We take our astonishing visual capabilities so much for granted that few of us ever stop to consider how we actually see. For decades, scientists have likened our visual-processing machinery to a television camera: the eye’s lens focuses incoming light onto an array of photoreceptors in the retina. These light detectors magically convert those photons into electrical signals that are sent along the optic nerve to the brain for processing. But recent experiments by the two of us and others indicate that this analogy is inadequate. The retina actually performs a significant amount of preprocessing right inside the eye and then sends a series of partial representations to the brain for interpretation.

We came to this surprising conclusion after investigating the retinas of rabbits, which are remarkably similar to those in humans. (Our work with salamanders has led to similar results.) The retina, it appears, is a tiny crescent of brain matter that has been brought out to the periphery to gain more direct access to the world…

Read the full article here Scientific American (pdf)